1. Field of the Invention
The present invention relates, in general, to automatic watthour meter reading apparatus and, specifically, to watthour meter socket adapters.
2. Description of the Art
In the electric utility industry, plug-in, socket-type watthour meters are commonly used to measure electric power consumption at residential or commercial sites. A socket housing is mounted on a convenient wall of the residence or commercial building and contains pairs of line and load terminals which are respectively connected to electric line and load conductors. The terminals receive blade contacts on a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals.
Plug-in socket adapters and socket adapters/extenders, both hereafter referred to simply as socket adapters, are designed to plug into the meter socket housing terminals. Such socket adapters are employed to convert ringless style sockets to ring style sockets or to extend the mounting position of the jaw terminals in the socket housing outward from the socket housing for mounting various electrical equipment, such as test devices or survey recorders, in the socket housing.
Such socket adapters employ a generally annular base having a shell joined thereto and extending outward from one side of the base. Contacts are mounted in the shell and base. Each contact has a female jaw portion disposed interiorly within the shell and a male blade terminal connected to the female jaw portion and extending outward from the shell and the base for a plug-in connection to the terminals in the meter socket housing.
Such socket adapters may be employed in both ring style and ringless style socket housings. In a ring style housing, a raised mounting flange is formed on the front cover of the socket housing to which the peripheral edge of the base of the socket adapter mates and is locked thereto by means of a conventional, annular, lockable sealing ring. In a ringless style socket housing, the peripheral edge flange of the base of the socket adapter is disposed interiorly within the socket housing in close proximity to or engagement with a raised annular portion of the cover surrounding an aperture through which the shell portion of the socket adapter extends. In both ringless and ring style socket housings, a separate sealing ring is mounted about a end mounting flange at the outer end of the shell to lockably mount a watthour meter to the socket adapter.
However, since the shell portion of such socket adapters extends outward from the cover of the socket housing, the plastic construction of the shell and the shoulder between the shell and the enlarged peripheral edge flange of the base presents an inviting location for tampering with the socket. A person seeking to tap unmetered power from the socket can drill a hole in the plastic sidewall of the shell portion of the socket adapter and insert a wire therethrough into contact with a line contact in the socket adapter. Alternately, a heated wire may be placed in contact with the sidewall of the shell to melt the plastic shell and to enable the wire to be forced inside the socket adapter. Careful manipulation of the wire can make a connection with a line contact within the socket adapter thereby providing unmetered power.
The shoulder between the shell and the peripheral edge flange of the base of the socket adapter presents another area for possible tampering. In a ringless style socket, a small gap can be formed between the sidewall of the shell and the peripheral edge of the opening in the cover of the socket housing thereby exposing a portion of the peripheral edge of the base through which a heated wire can be forced to connect to a line contact within the socket housing. In a ring style socket adapter employing sealing rings, manufacturing tolerances in the sealing rings and the socket adapter itself can create small gaps between the sealing ring and the exterior surface of the sidewall of the shell, again providing an opportunity for insertion of a heated wire through the shell and/or base of the socket adapter into the interior of the socket housing.
What is needed is a watthour meter socket adapter having improved tampering resistance and tampering detection. Thus, it would be desirable to provide a watthour meter socket adapter having improved tamper resistance which does not require extensive modification to the existing socket adapter design. It would also be desirable to provide a watthour meter socket adapter having improved tamper resistance which can be manufactured at a low cost and which can be easily used to provide tamper resistant features for such socket adapters.